Line data Source code
1 : //! An ImageLayer represents an image or a snapshot of a key-range at
2 : //! one particular LSN. It contains an image of all key-value pairs
3 : //! in its key-range. Any key that falls into the image layer's range
4 : //! but does not exist in the layer, does not exist.
5 : //!
6 : //! An image layer is stored in a file on disk. The file is stored in
7 : //! timelines/<timeline_id> directory. Currently, there are no
8 : //! subdirectories, and each image layer file is named like this:
9 : //!
10 : //! ```text
11 : //! <key start>-<key end>__<LSN>
12 : //! ```
13 : //!
14 : //! For example:
15 : //!
16 : //! ```text
17 : //! 000000067F000032BE0000400000000070B6-000000067F000032BE0000400000000080B6__00000000346BC568
18 : //! ```
19 : //!
20 : //! Every image layer file consists of three parts: "summary",
21 : //! "index", and "values". The summary is a fixed size header at the
22 : //! beginning of the file, and it contains basic information about the
23 : //! layer, and offsets to the other parts. The "index" is a B-tree,
24 : //! mapping from Key to an offset in the "values" part. The
25 : //! actual page images are stored in the "values" part.
26 : use crate::config::PageServerConf;
27 : use crate::context::{PageContentKind, RequestContext, RequestContextBuilder};
28 : use crate::page_cache::{self, FileId, PAGE_SZ};
29 : use crate::repository::{Key, Value, KEY_SIZE};
30 : use crate::tenant::blob_io::BlobWriter;
31 : use crate::tenant::block_io::{BlockBuf, BlockReader, FileBlockReader};
32 : use crate::tenant::disk_btree::{DiskBtreeBuilder, DiskBtreeReader, VisitDirection};
33 : use crate::tenant::storage_layer::{
34 : LayerAccessStats, ValueReconstructResult, ValueReconstructState,
35 : };
36 : use crate::tenant::timeline::GetVectoredError;
37 : use crate::tenant::vectored_blob_io::{
38 : BlobFlag, MaxVectoredReadBytes, VectoredBlobReader, VectoredRead, VectoredReadPlanner,
39 : };
40 : use crate::tenant::{PageReconstructError, Timeline};
41 : use crate::virtual_file::{self, VirtualFile};
42 : use crate::{IMAGE_FILE_MAGIC, STORAGE_FORMAT_VERSION, TEMP_FILE_SUFFIX};
43 : use anyhow::{anyhow, bail, ensure, Context, Result};
44 : use bytes::{Bytes, BytesMut};
45 : use camino::{Utf8Path, Utf8PathBuf};
46 : use hex;
47 : use itertools::Itertools;
48 : use pageserver_api::keyspace::KeySpace;
49 : use pageserver_api::models::LayerAccessKind;
50 : use pageserver_api::shard::{ShardIdentity, TenantShardId};
51 : use rand::{distributions::Alphanumeric, Rng};
52 : use serde::{Deserialize, Serialize};
53 : use std::fs::File;
54 : use std::io::SeekFrom;
55 : use std::ops::Range;
56 : use std::os::unix::prelude::FileExt;
57 : use std::str::FromStr;
58 : use std::sync::Arc;
59 : use tokio::sync::OnceCell;
60 : use tokio_stream::StreamExt;
61 : use tracing::*;
62 :
63 : use utils::{
64 : bin_ser::BeSer,
65 : id::{TenantId, TimelineId},
66 : lsn::Lsn,
67 : };
68 :
69 : use super::layer_name::ImageLayerName;
70 : use super::{
71 : AsLayerDesc, Layer, LayerName, PersistentLayerDesc, ResidentLayer, ValuesReconstructState,
72 : };
73 :
74 : ///
75 : /// Header stored in the beginning of the file
76 : ///
77 : /// After this comes the 'values' part, starting on block 1. After that,
78 : /// the 'index' starts at the block indicated by 'index_start_blk'
79 : ///
80 88 : #[derive(Debug, Serialize, Deserialize, PartialEq, Eq)]
81 : pub struct Summary {
82 : /// Magic value to identify this as a neon image file. Always IMAGE_FILE_MAGIC.
83 : pub magic: u16,
84 : pub format_version: u16,
85 :
86 : pub tenant_id: TenantId,
87 : pub timeline_id: TimelineId,
88 : pub key_range: Range<Key>,
89 : pub lsn: Lsn,
90 :
91 : /// Block number where the 'index' part of the file begins.
92 : pub index_start_blk: u32,
93 : /// Block within the 'index', where the B-tree root page is stored
94 : pub index_root_blk: u32,
95 : // the 'values' part starts after the summary header, on block 1.
96 : }
97 :
98 : impl From<&ImageLayer> for Summary {
99 0 : fn from(layer: &ImageLayer) -> Self {
100 0 : Self::expected(
101 0 : layer.desc.tenant_shard_id.tenant_id,
102 0 : layer.desc.timeline_id,
103 0 : layer.desc.key_range.clone(),
104 0 : layer.lsn,
105 0 : )
106 0 : }
107 : }
108 :
109 : impl Summary {
110 88 : pub(super) fn expected(
111 88 : tenant_id: TenantId,
112 88 : timeline_id: TimelineId,
113 88 : key_range: Range<Key>,
114 88 : lsn: Lsn,
115 88 : ) -> Self {
116 88 : Self {
117 88 : magic: IMAGE_FILE_MAGIC,
118 88 : format_version: STORAGE_FORMAT_VERSION,
119 88 : tenant_id,
120 88 : timeline_id,
121 88 : key_range,
122 88 : lsn,
123 88 :
124 88 : index_start_blk: 0,
125 88 : index_root_blk: 0,
126 88 : }
127 88 : }
128 : }
129 :
130 : /// This is used only from `pagectl`. Within pageserver, all layers are
131 : /// [`crate::tenant::storage_layer::Layer`], which can hold an [`ImageLayerInner`].
132 : pub struct ImageLayer {
133 : path: Utf8PathBuf,
134 : pub desc: PersistentLayerDesc,
135 : // This entry contains an image of all pages as of this LSN, should be the same as desc.lsn
136 : pub lsn: Lsn,
137 : access_stats: LayerAccessStats,
138 : inner: OnceCell<ImageLayerInner>,
139 : }
140 :
141 : impl std::fmt::Debug for ImageLayer {
142 0 : fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
143 0 : use super::RangeDisplayDebug;
144 0 :
145 0 : f.debug_struct("ImageLayer")
146 0 : .field("key_range", &RangeDisplayDebug(&self.desc.key_range))
147 0 : .field("file_size", &self.desc.file_size)
148 0 : .field("lsn", &self.lsn)
149 0 : .field("inner", &self.inner)
150 0 : .finish()
151 0 : }
152 : }
153 :
154 : /// ImageLayer is the in-memory data structure associated with an on-disk image
155 : /// file.
156 : pub struct ImageLayerInner {
157 : // values copied from summary
158 : index_start_blk: u32,
159 : index_root_blk: u32,
160 :
161 : key_range: Range<Key>,
162 : lsn: Lsn,
163 :
164 : file: VirtualFile,
165 : file_id: FileId,
166 :
167 : max_vectored_read_bytes: Option<MaxVectoredReadBytes>,
168 : }
169 :
170 : impl std::fmt::Debug for ImageLayerInner {
171 0 : fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
172 0 : f.debug_struct("ImageLayerInner")
173 0 : .field("index_start_blk", &self.index_start_blk)
174 0 : .field("index_root_blk", &self.index_root_blk)
175 0 : .finish()
176 0 : }
177 : }
178 :
179 : impl ImageLayerInner {
180 0 : pub(super) async fn dump(&self, ctx: &RequestContext) -> anyhow::Result<()> {
181 0 : let block_reader = FileBlockReader::new(&self.file, self.file_id);
182 0 : let tree_reader = DiskBtreeReader::<_, KEY_SIZE>::new(
183 0 : self.index_start_blk,
184 0 : self.index_root_blk,
185 0 : block_reader,
186 0 : );
187 0 :
188 0 : tree_reader.dump().await?;
189 :
190 0 : tree_reader
191 0 : .visit(
192 0 : &[0u8; KEY_SIZE],
193 0 : VisitDirection::Forwards,
194 0 : |key, value| {
195 0 : println!("key: {} offset {}", hex::encode(key), value);
196 0 : true
197 0 : },
198 0 : ctx,
199 0 : )
200 0 : .await?;
201 :
202 0 : Ok(())
203 0 : }
204 : }
205 :
206 : /// Boilerplate to implement the Layer trait, always use layer_desc for persistent layers.
207 : impl std::fmt::Display for ImageLayer {
208 0 : fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
209 0 : write!(f, "{}", self.layer_desc().short_id())
210 0 : }
211 : }
212 :
213 : impl AsLayerDesc for ImageLayer {
214 0 : fn layer_desc(&self) -> &PersistentLayerDesc {
215 0 : &self.desc
216 0 : }
217 : }
218 :
219 : impl ImageLayer {
220 0 : pub(crate) async fn dump(&self, verbose: bool, ctx: &RequestContext) -> Result<()> {
221 0 : self.desc.dump();
222 0 :
223 0 : if !verbose {
224 0 : return Ok(());
225 0 : }
226 :
227 0 : let inner = self.load(LayerAccessKind::Dump, ctx).await?;
228 :
229 0 : inner.dump(ctx).await?;
230 :
231 0 : Ok(())
232 0 : }
233 :
234 238 : fn temp_path_for(
235 238 : conf: &PageServerConf,
236 238 : timeline_id: TimelineId,
237 238 : tenant_shard_id: TenantShardId,
238 238 : fname: &ImageLayerName,
239 238 : ) -> Utf8PathBuf {
240 238 : let rand_string: String = rand::thread_rng()
241 238 : .sample_iter(&Alphanumeric)
242 238 : .take(8)
243 238 : .map(char::from)
244 238 : .collect();
245 238 :
246 238 : conf.timeline_path(&tenant_shard_id, &timeline_id)
247 238 : .join(format!("{fname}.{rand_string}.{TEMP_FILE_SUFFIX}"))
248 238 : }
249 :
250 : ///
251 : /// Open the underlying file and read the metadata into memory, if it's
252 : /// not loaded already.
253 : ///
254 0 : async fn load(
255 0 : &self,
256 0 : access_kind: LayerAccessKind,
257 0 : ctx: &RequestContext,
258 0 : ) -> Result<&ImageLayerInner> {
259 0 : self.access_stats.record_access(access_kind, ctx);
260 0 : self.inner
261 0 : .get_or_try_init(|| self.load_inner(ctx))
262 0 : .await
263 0 : .with_context(|| format!("Failed to load image layer {}", self.path()))
264 0 : }
265 :
266 0 : async fn load_inner(&self, ctx: &RequestContext) -> Result<ImageLayerInner> {
267 0 : let path = self.path();
268 :
269 0 : let loaded = ImageLayerInner::load(&path, self.desc.image_layer_lsn(), None, None, ctx)
270 0 : .await
271 0 : .and_then(|res| res)?;
272 :
273 : // not production code
274 0 : let actual_layer_name = LayerName::from_str(path.file_name().unwrap()).unwrap();
275 0 : let expected_layer_name = self.layer_desc().layer_name();
276 0 :
277 0 : if actual_layer_name != expected_layer_name {
278 0 : println!("warning: filename does not match what is expected from in-file summary");
279 0 : println!("actual: {:?}", actual_layer_name.to_string());
280 0 : println!("expected: {:?}", expected_layer_name.to_string());
281 0 : }
282 :
283 0 : Ok(loaded)
284 0 : }
285 :
286 : /// Create an ImageLayer struct representing an existing file on disk.
287 : ///
288 : /// This variant is only used for debugging purposes, by the 'pagectl' binary.
289 0 : pub fn new_for_path(path: &Utf8Path, file: File) -> Result<ImageLayer> {
290 0 : let mut summary_buf = vec![0; PAGE_SZ];
291 0 : file.read_exact_at(&mut summary_buf, 0)?;
292 0 : let summary = Summary::des_prefix(&summary_buf)?;
293 0 : let metadata = file
294 0 : .metadata()
295 0 : .context("get file metadata to determine size")?;
296 :
297 : // This function is never used for constructing layers in a running pageserver,
298 : // so it does not need an accurate TenantShardId.
299 0 : let tenant_shard_id = TenantShardId::unsharded(summary.tenant_id);
300 0 :
301 0 : Ok(ImageLayer {
302 0 : path: path.to_path_buf(),
303 0 : desc: PersistentLayerDesc::new_img(
304 0 : tenant_shard_id,
305 0 : summary.timeline_id,
306 0 : summary.key_range,
307 0 : summary.lsn,
308 0 : metadata.len(),
309 0 : ), // Now we assume image layer ALWAYS covers the full range. This may change in the future.
310 0 : lsn: summary.lsn,
311 0 : access_stats: LayerAccessStats::empty_will_record_residence_event_later(),
312 0 : inner: OnceCell::new(),
313 0 : })
314 0 : }
315 :
316 0 : fn path(&self) -> Utf8PathBuf {
317 0 : self.path.clone()
318 0 : }
319 : }
320 :
321 0 : #[derive(thiserror::Error, Debug)]
322 : pub enum RewriteSummaryError {
323 : #[error("magic mismatch")]
324 : MagicMismatch,
325 : #[error(transparent)]
326 : Other(#[from] anyhow::Error),
327 : }
328 :
329 : impl From<std::io::Error> for RewriteSummaryError {
330 0 : fn from(e: std::io::Error) -> Self {
331 0 : Self::Other(anyhow::anyhow!(e))
332 0 : }
333 : }
334 :
335 : impl ImageLayer {
336 0 : pub async fn rewrite_summary<F>(
337 0 : path: &Utf8Path,
338 0 : rewrite: F,
339 0 : ctx: &RequestContext,
340 0 : ) -> Result<(), RewriteSummaryError>
341 0 : where
342 0 : F: Fn(Summary) -> Summary,
343 0 : {
344 0 : let mut file = VirtualFile::open_with_options(
345 0 : path,
346 0 : virtual_file::OpenOptions::new().read(true).write(true),
347 0 : ctx,
348 0 : )
349 0 : .await
350 0 : .with_context(|| format!("Failed to open file '{}'", path))?;
351 0 : let file_id = page_cache::next_file_id();
352 0 : let block_reader = FileBlockReader::new(&file, file_id);
353 0 : let summary_blk = block_reader.read_blk(0, ctx).await?;
354 0 : let actual_summary = Summary::des_prefix(summary_blk.as_ref()).context("deserialize")?;
355 0 : if actual_summary.magic != IMAGE_FILE_MAGIC {
356 0 : return Err(RewriteSummaryError::MagicMismatch);
357 0 : }
358 0 :
359 0 : let new_summary = rewrite(actual_summary);
360 0 :
361 0 : let mut buf = Vec::with_capacity(PAGE_SZ);
362 0 : // TODO: could use smallvec here but it's a pain with Slice<T>
363 0 : Summary::ser_into(&new_summary, &mut buf).context("serialize")?;
364 0 : file.seek(SeekFrom::Start(0)).await?;
365 0 : let (_buf, res) = file.write_all(buf, ctx).await;
366 0 : res?;
367 0 : Ok(())
368 0 : }
369 : }
370 :
371 : impl ImageLayerInner {
372 : /// Returns nested result following Result<Result<_, OpErr>, Critical>:
373 : /// - inner has the success or transient failure
374 : /// - outer has the permanent failure
375 88 : pub(super) async fn load(
376 88 : path: &Utf8Path,
377 88 : lsn: Lsn,
378 88 : summary: Option<Summary>,
379 88 : max_vectored_read_bytes: Option<MaxVectoredReadBytes>,
380 88 : ctx: &RequestContext,
381 88 : ) -> Result<Result<Self, anyhow::Error>, anyhow::Error> {
382 88 : let file = match VirtualFile::open(path, ctx).await {
383 88 : Ok(file) => file,
384 0 : Err(e) => return Ok(Err(anyhow::Error::new(e).context("open layer file"))),
385 : };
386 88 : let file_id = page_cache::next_file_id();
387 88 : let block_reader = FileBlockReader::new(&file, file_id);
388 88 : let summary_blk = match block_reader.read_blk(0, ctx).await {
389 88 : Ok(blk) => blk,
390 0 : Err(e) => return Ok(Err(anyhow::Error::new(e).context("read first block"))),
391 : };
392 :
393 : // length is the only way how this could fail, so it's not actually likely at all unless
394 : // read_blk returns wrong sized block.
395 : //
396 : // TODO: confirm and make this into assertion
397 88 : let actual_summary =
398 88 : Summary::des_prefix(summary_blk.as_ref()).context("deserialize first block")?;
399 :
400 88 : if let Some(mut expected_summary) = summary {
401 : // production code path
402 88 : expected_summary.index_start_blk = actual_summary.index_start_blk;
403 88 : expected_summary.index_root_blk = actual_summary.index_root_blk;
404 88 : // mask out the timeline_id, but still require the layers to be from the same tenant
405 88 : expected_summary.timeline_id = actual_summary.timeline_id;
406 88 :
407 88 : if actual_summary != expected_summary {
408 0 : bail!(
409 0 : "in-file summary does not match expected summary. actual = {:?} expected = {:?}",
410 0 : actual_summary,
411 0 : expected_summary
412 0 : );
413 88 : }
414 0 : }
415 :
416 88 : Ok(Ok(ImageLayerInner {
417 88 : index_start_blk: actual_summary.index_start_blk,
418 88 : index_root_blk: actual_summary.index_root_blk,
419 88 : lsn,
420 88 : file,
421 88 : file_id,
422 88 : max_vectored_read_bytes,
423 88 : key_range: actual_summary.key_range,
424 88 : }))
425 88 : }
426 :
427 7187 : pub(super) async fn get_value_reconstruct_data(
428 7187 : &self,
429 7187 : key: Key,
430 7187 : reconstruct_state: &mut ValueReconstructState,
431 7187 : ctx: &RequestContext,
432 7187 : ) -> anyhow::Result<ValueReconstructResult> {
433 7187 : let block_reader = FileBlockReader::new(&self.file, self.file_id);
434 7187 : let tree_reader =
435 7187 : DiskBtreeReader::new(self.index_start_blk, self.index_root_blk, &block_reader);
436 7187 :
437 7187 : let mut keybuf: [u8; KEY_SIZE] = [0u8; KEY_SIZE];
438 7187 : key.write_to_byte_slice(&mut keybuf);
439 7187 : if let Some(offset) = tree_reader
440 7187 : .get(
441 7187 : &keybuf,
442 7187 : &RequestContextBuilder::extend(ctx)
443 7187 : .page_content_kind(PageContentKind::ImageLayerBtreeNode)
444 7187 : .build(),
445 7187 : )
446 430 : .await?
447 : {
448 7183 : let blob = block_reader
449 7183 : .block_cursor()
450 7183 : .read_blob(
451 7183 : offset,
452 7183 : &RequestContextBuilder::extend(ctx)
453 7183 : .page_content_kind(PageContentKind::ImageLayerValue)
454 7183 : .build(),
455 7183 : )
456 317 : .await
457 7183 : .with_context(|| format!("failed to read value from offset {}", offset))?;
458 7183 : let value = Bytes::from(blob);
459 7183 :
460 7183 : reconstruct_state.img = Some((self.lsn, value));
461 7183 : Ok(ValueReconstructResult::Complete)
462 : } else {
463 4 : Ok(ValueReconstructResult::Missing)
464 : }
465 7187 : }
466 :
467 : // Look up the keys in the provided keyspace and update
468 : // the reconstruct state with whatever is found.
469 74 : pub(super) async fn get_values_reconstruct_data(
470 74 : &self,
471 74 : keyspace: KeySpace,
472 74 : reconstruct_state: &mut ValuesReconstructState,
473 74 : ctx: &RequestContext,
474 74 : ) -> Result<(), GetVectoredError> {
475 74 : let reads = self
476 74 : .plan_reads(keyspace, None, ctx)
477 343 : .await
478 74 : .map_err(GetVectoredError::Other)?;
479 :
480 74 : self.do_reads_and_update_state(reads, reconstruct_state, ctx)
481 894 : .await;
482 :
483 74 : reconstruct_state.on_image_layer_visited(&self.key_range);
484 74 :
485 74 : Ok(())
486 74 : }
487 :
488 : /// Load all key-values in the delta layer, should be replaced by an iterator-based interface in the future.
489 : #[cfg(test)]
490 8 : pub(super) async fn load_key_values(
491 8 : &self,
492 8 : ctx: &RequestContext,
493 8 : ) -> anyhow::Result<Vec<(Key, Lsn, Value)>> {
494 8 : let block_reader = FileBlockReader::new(&self.file, self.file_id);
495 8 : let tree_reader =
496 8 : DiskBtreeReader::new(self.index_start_blk, self.index_root_blk, &block_reader);
497 8 : let mut result = Vec::new();
498 8 : let mut stream = Box::pin(tree_reader.get_stream_from(&[0; KEY_SIZE], ctx));
499 8 : let block_reader = FileBlockReader::new(&self.file, self.file_id);
500 8 : let cursor = block_reader.block_cursor();
501 80 : while let Some(item) = stream.next().await {
502 : // TODO: dedup code with get_reconstruct_value
503 72 : let (raw_key, offset) = item?;
504 72 : let key = Key::from_slice(&raw_key[..KEY_SIZE]);
505 : // TODO: ctx handling and sharding
506 72 : let blob = cursor
507 72 : .read_blob(offset, ctx)
508 2 : .await
509 72 : .with_context(|| format!("failed to read value from offset {}", offset))?;
510 72 : let value = Bytes::from(blob);
511 72 : result.push((key, self.lsn, Value::Image(value)));
512 : }
513 8 : Ok(result)
514 8 : }
515 :
516 : /// Traverse the layer's index to build read operations on the overlap of the input keyspace
517 : /// and the keys in this layer.
518 : ///
519 : /// If shard_identity is provided, it will be used to filter keys down to those stored on
520 : /// this shard.
521 82 : async fn plan_reads(
522 82 : &self,
523 82 : keyspace: KeySpace,
524 82 : shard_identity: Option<&ShardIdentity>,
525 82 : ctx: &RequestContext,
526 82 : ) -> anyhow::Result<Vec<VectoredRead>> {
527 82 : let mut planner = VectoredReadPlanner::new(
528 82 : self.max_vectored_read_bytes
529 82 : .expect("Layer is loaded with max vectored bytes config")
530 82 : .0
531 82 : .into(),
532 82 : );
533 82 :
534 82 : let block_reader = FileBlockReader::new(&self.file, self.file_id);
535 82 : let tree_reader =
536 82 : DiskBtreeReader::new(self.index_start_blk, self.index_root_blk, block_reader);
537 82 :
538 82 : let ctx = RequestContextBuilder::extend(ctx)
539 82 : .page_content_kind(PageContentKind::ImageLayerBtreeNode)
540 82 : .build();
541 :
542 21668 : for range in keyspace.ranges.iter() {
543 21668 : let mut range_end_handled = false;
544 21668 : let mut search_key: [u8; KEY_SIZE] = [0u8; KEY_SIZE];
545 21668 : range.start.write_to_byte_slice(&mut search_key);
546 21668 :
547 21668 : let index_stream = tree_reader.get_stream_from(&search_key, &ctx);
548 21668 : let mut index_stream = std::pin::pin!(index_stream);
549 :
550 1080721 : while let Some(index_entry) = index_stream.next().await {
551 1080661 : let (raw_key, offset) = index_entry?;
552 :
553 1080661 : let key = Key::from_slice(&raw_key[..KEY_SIZE]);
554 1080661 : assert!(key >= range.start);
555 :
556 1080661 : let flag = if let Some(shard_identity) = shard_identity {
557 1048576 : if shard_identity.is_key_disposable(&key) {
558 786432 : BlobFlag::Ignore
559 : } else {
560 262144 : BlobFlag::None
561 : }
562 : } else {
563 32085 : BlobFlag::None
564 : };
565 :
566 1080661 : if key >= range.end {
567 21608 : planner.handle_range_end(offset);
568 21608 : range_end_handled = true;
569 21608 : break;
570 1059053 : } else {
571 1059053 : planner.handle(key, self.lsn, offset, flag);
572 1059053 : }
573 : }
574 :
575 21668 : if !range_end_handled {
576 60 : let payload_end = self.index_start_blk as u64 * PAGE_SZ as u64;
577 60 : planner.handle_range_end(payload_end);
578 21608 : }
579 : }
580 :
581 82 : Ok(planner.finish())
582 82 : }
583 :
584 : /// Given a key range, select the parts of that range that should be retained by the ShardIdentity,
585 : /// then execute vectored GET operations, passing the results of all read keys into the writer.
586 8 : pub(super) async fn filter(
587 8 : &self,
588 8 : shard_identity: &ShardIdentity,
589 8 : writer: &mut ImageLayerWriter,
590 8 : ctx: &RequestContext,
591 8 : ) -> anyhow::Result<usize> {
592 : // Fragment the range into the regions owned by this ShardIdentity
593 8 : let plan = self
594 8 : .plan_reads(
595 8 : KeySpace {
596 8 : // If asked for the total key space, plan_reads will give us all the keys in the layer
597 8 : ranges: vec![Key::MIN..Key::MAX],
598 8 : },
599 8 : Some(shard_identity),
600 8 : ctx,
601 8 : )
602 469 : .await?;
603 :
604 8 : let vectored_blob_reader = VectoredBlobReader::new(&self.file);
605 8 : let mut key_count = 0;
606 16 : for read in plan.into_iter() {
607 16 : let buf_size = read.size();
608 16 :
609 16 : let buf = BytesMut::with_capacity(buf_size);
610 16 : let blobs_buf = vectored_blob_reader.read_blobs(&read, buf, ctx).await?;
611 :
612 16 : let frozen_buf = blobs_buf.buf.freeze();
613 :
614 262144 : for meta in blobs_buf.blobs.iter() {
615 262144 : let img_buf = frozen_buf.slice(meta.start..meta.end);
616 262144 :
617 262144 : key_count += 1;
618 262144 : writer
619 262144 : .put_image(meta.meta.key, img_buf, ctx)
620 266240 : .await
621 262144 : .context(format!("Storing key {}", meta.meta.key))?;
622 : }
623 : }
624 :
625 8 : Ok(key_count)
626 8 : }
627 :
628 74 : async fn do_reads_and_update_state(
629 74 : &self,
630 74 : reads: Vec<VectoredRead>,
631 74 : reconstruct_state: &mut ValuesReconstructState,
632 74 : ctx: &RequestContext,
633 74 : ) {
634 74 : let max_vectored_read_bytes = self
635 74 : .max_vectored_read_bytes
636 74 : .expect("Layer is loaded with max vectored bytes config")
637 74 : .0
638 74 : .into();
639 74 :
640 74 : let vectored_blob_reader = VectoredBlobReader::new(&self.file);
641 1772 : for read in reads.into_iter() {
642 1772 : let buf_size = read.size();
643 1772 :
644 1772 : if buf_size > max_vectored_read_bytes {
645 : // If the read is oversized, it should only contain one key.
646 0 : let offenders = read
647 0 : .blobs_at
648 0 : .as_slice()
649 0 : .iter()
650 0 : .map(|(_, blob_meta)| format!("{}@{}", blob_meta.key, blob_meta.lsn))
651 0 : .join(", ");
652 0 : tracing::warn!(
653 0 : "Oversized vectored read ({} > {}) for keys {}",
654 : buf_size,
655 : max_vectored_read_bytes,
656 : offenders
657 : );
658 1772 : }
659 :
660 1772 : let buf = BytesMut::with_capacity(buf_size);
661 1772 : let res = vectored_blob_reader.read_blobs(&read, buf, ctx).await;
662 :
663 1772 : match res {
664 1772 : Ok(blobs_buf) => {
665 1772 : let frozen_buf = blobs_buf.buf.freeze();
666 :
667 10477 : for meta in blobs_buf.blobs.iter() {
668 10477 : let img_buf = frozen_buf.slice(meta.start..meta.end);
669 10477 : reconstruct_state.update_key(
670 10477 : &meta.meta.key,
671 10477 : self.lsn,
672 10477 : Value::Image(img_buf),
673 10477 : );
674 10477 : }
675 : }
676 0 : Err(err) => {
677 0 : let kind = err.kind();
678 0 : for (_, blob_meta) in read.blobs_at.as_slice() {
679 0 : reconstruct_state.on_key_error(
680 0 : blob_meta.key,
681 0 : PageReconstructError::from(anyhow!(
682 0 : "Failed to read blobs from virtual file {}: {}",
683 0 : self.file.path,
684 0 : kind
685 0 : )),
686 0 : );
687 0 : }
688 : }
689 : };
690 : }
691 74 : }
692 : }
693 :
694 : /// A builder object for constructing a new image layer.
695 : ///
696 : /// Usage:
697 : ///
698 : /// 1. Create the ImageLayerWriter by calling ImageLayerWriter::new(...)
699 : ///
700 : /// 2. Write the contents by calling `put_page_image` for every key-value
701 : /// pair in the key range.
702 : ///
703 : /// 3. Call `finish`.
704 : ///
705 : struct ImageLayerWriterInner {
706 : conf: &'static PageServerConf,
707 : path: Utf8PathBuf,
708 : timeline_id: TimelineId,
709 : tenant_shard_id: TenantShardId,
710 : key_range: Range<Key>,
711 : lsn: Lsn,
712 :
713 : blob_writer: BlobWriter<false>,
714 : tree: DiskBtreeBuilder<BlockBuf, KEY_SIZE>,
715 : }
716 :
717 : impl ImageLayerWriterInner {
718 : ///
719 : /// Start building a new image layer.
720 : ///
721 238 : async fn new(
722 238 : conf: &'static PageServerConf,
723 238 : timeline_id: TimelineId,
724 238 : tenant_shard_id: TenantShardId,
725 238 : key_range: &Range<Key>,
726 238 : lsn: Lsn,
727 238 : ctx: &RequestContext,
728 238 : ) -> anyhow::Result<Self> {
729 238 : // Create the file initially with a temporary filename.
730 238 : // We'll atomically rename it to the final name when we're done.
731 238 : let path = ImageLayer::temp_path_for(
732 238 : conf,
733 238 : timeline_id,
734 238 : tenant_shard_id,
735 238 : &ImageLayerName {
736 238 : key_range: key_range.clone(),
737 238 : lsn,
738 238 : },
739 238 : );
740 238 : trace!("creating image layer {}", path);
741 238 : let mut file = {
742 238 : VirtualFile::open_with_options(
743 238 : &path,
744 238 : virtual_file::OpenOptions::new()
745 238 : .write(true)
746 238 : .create_new(true),
747 238 : ctx,
748 238 : )
749 184 : .await?
750 : };
751 : // make room for the header block
752 238 : file.seek(SeekFrom::Start(PAGE_SZ as u64)).await?;
753 238 : let blob_writer = BlobWriter::new(file, PAGE_SZ as u64);
754 238 :
755 238 : // Initialize the b-tree index builder
756 238 : let block_buf = BlockBuf::new();
757 238 : let tree_builder = DiskBtreeBuilder::new(block_buf);
758 238 :
759 238 : let writer = Self {
760 238 : conf,
761 238 : path,
762 238 : timeline_id,
763 238 : tenant_shard_id,
764 238 : key_range: key_range.clone(),
765 238 : lsn,
766 238 : tree: tree_builder,
767 238 : blob_writer,
768 238 : };
769 238 :
770 238 : Ok(writer)
771 238 : }
772 :
773 : ///
774 : /// Write next value to the file.
775 : ///
776 : /// The page versions must be appended in blknum order.
777 : ///
778 535686 : async fn put_image(
779 535686 : &mut self,
780 535686 : key: Key,
781 535686 : img: Bytes,
782 535686 : ctx: &RequestContext,
783 535686 : ) -> anyhow::Result<()> {
784 535686 : ensure!(self.key_range.contains(&key));
785 544170 : let (_img, res) = self.blob_writer.write_blob(img, ctx).await;
786 : // TODO: re-use the buffer for `img` further upstack
787 535686 : let off = res?;
788 :
789 535686 : let mut keybuf: [u8; KEY_SIZE] = [0u8; KEY_SIZE];
790 535686 : key.write_to_byte_slice(&mut keybuf);
791 535686 : self.tree.append(&keybuf, off)?;
792 :
793 535686 : Ok(())
794 535686 : }
795 :
796 : ///
797 : /// Finish writing the image layer.
798 : ///
799 232 : async fn finish(
800 232 : self,
801 232 : timeline: &Arc<Timeline>,
802 232 : ctx: &RequestContext,
803 232 : ) -> anyhow::Result<ResidentLayer> {
804 232 : let index_start_blk =
805 232 : ((self.blob_writer.size() + PAGE_SZ as u64 - 1) / PAGE_SZ as u64) as u32;
806 232 :
807 232 : let mut file = self.blob_writer.into_inner();
808 232 :
809 232 : // Write out the index
810 232 : file.seek(SeekFrom::Start(index_start_blk as u64 * PAGE_SZ as u64))
811 0 : .await?;
812 232 : let (index_root_blk, block_buf) = self.tree.finish()?;
813 920 : for buf in block_buf.blocks {
814 688 : let (_buf, res) = file.write_all(buf, ctx).await;
815 688 : res?;
816 : }
817 :
818 : // Fill in the summary on blk 0
819 232 : let summary = Summary {
820 232 : magic: IMAGE_FILE_MAGIC,
821 232 : format_version: STORAGE_FORMAT_VERSION,
822 232 : tenant_id: self.tenant_shard_id.tenant_id,
823 232 : timeline_id: self.timeline_id,
824 232 : key_range: self.key_range.clone(),
825 232 : lsn: self.lsn,
826 232 : index_start_blk,
827 232 : index_root_blk,
828 232 : };
829 232 :
830 232 : let mut buf = Vec::with_capacity(PAGE_SZ);
831 232 : // TODO: could use smallvec here but it's a pain with Slice<T>
832 232 : Summary::ser_into(&summary, &mut buf)?;
833 232 : file.seek(SeekFrom::Start(0)).await?;
834 232 : let (_buf, res) = file.write_all(buf, ctx).await;
835 232 : res?;
836 :
837 232 : let metadata = file
838 232 : .metadata()
839 119 : .await
840 232 : .context("get metadata to determine file size")?;
841 :
842 232 : let desc = PersistentLayerDesc::new_img(
843 232 : self.tenant_shard_id,
844 232 : self.timeline_id,
845 232 : self.key_range.clone(),
846 232 : self.lsn,
847 232 : metadata.len(),
848 232 : );
849 232 :
850 232 : // Note: Because we open the file in write-only mode, we cannot
851 232 : // reuse the same VirtualFile for reading later. That's why we don't
852 232 : // set inner.file here. The first read will have to re-open it.
853 232 :
854 232 : // fsync the file
855 232 : file.sync_all().await?;
856 :
857 : // FIXME: why not carry the virtualfile here, it supports renaming?
858 232 : let layer = Layer::finish_creating(self.conf, timeline, desc, &self.path)?;
859 :
860 232 : info!("created image layer {}", layer.local_path());
861 :
862 232 : Ok(layer)
863 232 : }
864 : }
865 :
866 : /// A builder object for constructing a new image layer.
867 : ///
868 : /// Usage:
869 : ///
870 : /// 1. Create the ImageLayerWriter by calling ImageLayerWriter::new(...)
871 : ///
872 : /// 2. Write the contents by calling `put_page_image` for every key-value
873 : /// pair in the key range.
874 : ///
875 : /// 3. Call `finish`.
876 : ///
877 : /// # Note
878 : ///
879 : /// As described in <https://github.com/neondatabase/neon/issues/2650>, it's
880 : /// possible for the writer to drop before `finish` is actually called. So this
881 : /// could lead to odd temporary files in the directory, exhausting file system.
882 : /// This structure wraps `ImageLayerWriterInner` and also contains `Drop`
883 : /// implementation that cleans up the temporary file in failure. It's not
884 : /// possible to do this directly in `ImageLayerWriterInner` since `finish` moves
885 : /// out some fields, making it impossible to implement `Drop`.
886 : ///
887 : #[must_use]
888 : pub struct ImageLayerWriter {
889 : inner: Option<ImageLayerWriterInner>,
890 : }
891 :
892 : impl ImageLayerWriter {
893 : ///
894 : /// Start building a new image layer.
895 : ///
896 238 : pub async fn new(
897 238 : conf: &'static PageServerConf,
898 238 : timeline_id: TimelineId,
899 238 : tenant_shard_id: TenantShardId,
900 238 : key_range: &Range<Key>,
901 238 : lsn: Lsn,
902 238 : ctx: &RequestContext,
903 238 : ) -> anyhow::Result<ImageLayerWriter> {
904 238 : Ok(Self {
905 238 : inner: Some(
906 238 : ImageLayerWriterInner::new(conf, timeline_id, tenant_shard_id, key_range, lsn, ctx)
907 184 : .await?,
908 : ),
909 : })
910 238 : }
911 :
912 : ///
913 : /// Write next value to the file.
914 : ///
915 : /// The page versions must be appended in blknum order.
916 : ///
917 535686 : pub async fn put_image(
918 535686 : &mut self,
919 535686 : key: Key,
920 535686 : img: Bytes,
921 535686 : ctx: &RequestContext,
922 535686 : ) -> anyhow::Result<()> {
923 544170 : self.inner.as_mut().unwrap().put_image(key, img, ctx).await
924 535686 : }
925 :
926 : ///
927 : /// Finish writing the image layer.
928 : ///
929 232 : pub(crate) async fn finish(
930 232 : mut self,
931 232 : timeline: &Arc<Timeline>,
932 232 : ctx: &RequestContext,
933 232 : ) -> anyhow::Result<super::ResidentLayer> {
934 701 : self.inner.take().unwrap().finish(timeline, ctx).await
935 232 : }
936 : }
937 :
938 : impl Drop for ImageLayerWriter {
939 238 : fn drop(&mut self) {
940 238 : if let Some(inner) = self.inner.take() {
941 6 : inner.blob_writer.into_inner().remove();
942 232 : }
943 238 : }
944 : }
945 :
946 : #[cfg(test)]
947 : mod test {
948 : use std::time::Duration;
949 :
950 : use bytes::Bytes;
951 : use pageserver_api::{
952 : key::Key,
953 : shard::{ShardCount, ShardIdentity, ShardNumber, ShardStripeSize},
954 : };
955 : use utils::{
956 : generation::Generation,
957 : id::{TenantId, TimelineId},
958 : lsn::Lsn,
959 : };
960 :
961 : use crate::{
962 : tenant::{config::TenantConf, harness::TenantHarness},
963 : DEFAULT_PG_VERSION,
964 : };
965 :
966 : use super::ImageLayerWriter;
967 :
968 : #[tokio::test]
969 2 : async fn image_layer_rewrite() {
970 2 : let tenant_conf = TenantConf {
971 2 : gc_period: Duration::ZERO,
972 2 : compaction_period: Duration::ZERO,
973 2 : ..TenantConf::default()
974 2 : };
975 2 : let tenant_id = TenantId::generate();
976 2 : let mut gen = Generation::new(0xdead0001);
977 10 : let mut get_next_gen = || {
978 10 : let ret = gen;
979 10 : gen = gen.next();
980 10 : ret
981 10 : };
982 2 : // The LSN at which we will create an image layer to filter
983 2 : let lsn = Lsn(0xdeadbeef0000);
984 2 : let timeline_id = TimelineId::generate();
985 2 :
986 2 : //
987 2 : // Create an unsharded parent with a layer.
988 2 : //
989 2 :
990 2 : let harness = TenantHarness::create_custom(
991 2 : "test_image_layer_rewrite--parent",
992 2 : tenant_conf.clone(),
993 2 : tenant_id,
994 2 : ShardIdentity::unsharded(),
995 2 : get_next_gen(),
996 2 : )
997 2 : .unwrap();
998 8 : let (tenant, ctx) = harness.load().await;
999 2 : let timeline = tenant
1000 2 : .create_test_timeline(timeline_id, lsn, DEFAULT_PG_VERSION, &ctx)
1001 6 : .await
1002 2 : .unwrap();
1003 2 :
1004 2 : // This key range contains several 0x8000 page stripes, only one of which belongs to shard zero
1005 2 : let input_start = Key::from_hex("000000067f00000001000000ae0000000000").unwrap();
1006 2 : let input_end = Key::from_hex("000000067f00000001000000ae0000020000").unwrap();
1007 2 : let range = input_start..input_end;
1008 2 :
1009 2 : // Build an image layer to filter
1010 2 : let resident = {
1011 2 : let mut writer = ImageLayerWriter::new(
1012 2 : harness.conf,
1013 2 : timeline_id,
1014 2 : harness.tenant_shard_id,
1015 2 : &range,
1016 2 : lsn,
1017 2 : &ctx,
1018 2 : )
1019 2 : .await
1020 2 : .unwrap();
1021 2 :
1022 2 : let foo_img = Bytes::from_static(&[1, 2, 3, 4]);
1023 2 : let mut key = range.start;
1024 262146 : while key < range.end {
1025 266239 : writer.put_image(key, foo_img.clone(), &ctx).await.unwrap();
1026 262144 :
1027 262144 : key = key.next();
1028 2 : }
1029 119 : writer.finish(&timeline, &ctx).await.unwrap()
1030 2 : };
1031 2 : let original_size = resident.metadata().file_size;
1032 2 :
1033 2 : //
1034 2 : // Create child shards and do the rewrite, exercising filter().
1035 2 : // TODO: abstraction in TenantHarness for splits.
1036 2 : //
1037 2 :
1038 2 : // Filter for various shards: this exercises cases like values at start of key range, end of key
1039 2 : // range, middle of key range.
1040 2 : let shard_count = ShardCount::new(4);
1041 8 : for shard_number in 0..shard_count.count() {
1042 2 : //
1043 2 : // mimic the shard split
1044 2 : //
1045 8 : let shard_identity = ShardIdentity::new(
1046 8 : ShardNumber(shard_number),
1047 8 : shard_count,
1048 8 : ShardStripeSize(0x8000),
1049 8 : )
1050 8 : .unwrap();
1051 8 : let harness = TenantHarness::create_custom(
1052 8 : Box::leak(Box::new(format!(
1053 8 : "test_image_layer_rewrite--child{}",
1054 8 : shard_identity.shard_slug()
1055 8 : ))),
1056 8 : tenant_conf.clone(),
1057 8 : tenant_id,
1058 8 : shard_identity,
1059 8 : // NB: in reality, the shards would each fork off their own gen number sequence from the parent.
1060 8 : // But here, all we care about is that the gen number is unique.
1061 8 : get_next_gen(),
1062 8 : )
1063 8 : .unwrap();
1064 29 : let (tenant, ctx) = harness.load().await;
1065 8 : let timeline = tenant
1066 8 : .create_test_timeline(timeline_id, lsn, DEFAULT_PG_VERSION, &ctx)
1067 20 : .await
1068 8 : .unwrap();
1069 2 :
1070 2 : //
1071 2 : // use filter() and make assertions
1072 2 : //
1073 2 :
1074 8 : let mut filtered_writer = ImageLayerWriter::new(
1075 8 : harness.conf,
1076 8 : timeline_id,
1077 8 : harness.tenant_shard_id,
1078 8 : &range,
1079 8 : lsn,
1080 8 : &ctx,
1081 8 : )
1082 4 : .await
1083 8 : .unwrap();
1084 2 :
1085 8 : let wrote_keys = resident
1086 8 : .filter(&shard_identity, &mut filtered_writer, &ctx)
1087 266719 : .await
1088 8 : .unwrap();
1089 8 : let replacement = if wrote_keys > 0 {
1090 129 : Some(filtered_writer.finish(&timeline, &ctx).await.unwrap())
1091 2 : } else {
1092 2 : None
1093 2 : };
1094 2 :
1095 2 : // This exact size and those below will need updating as/when the layer encoding changes, but
1096 2 : // should be deterministic for a given version of the format, as we used no randomness generating the input.
1097 8 : assert_eq!(original_size, 1597440);
1098 2 :
1099 8 : match shard_number {
1100 2 : 0 => {
1101 2 : // We should have written out just one stripe for our shard identity
1102 2 : assert_eq!(wrote_keys, 0x8000);
1103 2 : let replacement = replacement.unwrap();
1104 2 :
1105 2 : // We should have dropped some of the data
1106 2 : assert!(replacement.metadata().file_size < original_size);
1107 2 : assert!(replacement.metadata().file_size > 0);
1108 2 :
1109 2 : // Assert that we dropped ~3/4 of the data.
1110 2 : assert_eq!(replacement.metadata().file_size, 417792);
1111 2 : }
1112 2 : 1 => {
1113 2 : // Shard 1 has no keys in our input range
1114 2 : assert_eq!(wrote_keys, 0x0);
1115 2 : assert!(replacement.is_none());
1116 2 : }
1117 2 : 2 => {
1118 2 : // Shard 2 has one stripes in the input range
1119 2 : assert_eq!(wrote_keys, 0x8000);
1120 2 : let replacement = replacement.unwrap();
1121 2 : assert!(replacement.metadata().file_size < original_size);
1122 2 : assert!(replacement.metadata().file_size > 0);
1123 2 : assert_eq!(replacement.metadata().file_size, 417792);
1124 2 : }
1125 2 : 3 => {
1126 2 : // Shard 3 has two stripes in the input range
1127 2 : assert_eq!(wrote_keys, 0x10000);
1128 2 : let replacement = replacement.unwrap();
1129 2 : assert!(replacement.metadata().file_size < original_size);
1130 2 : assert!(replacement.metadata().file_size > 0);
1131 2 : assert_eq!(replacement.metadata().file_size, 811008);
1132 2 : }
1133 2 : _ => unreachable!(),
1134 2 : }
1135 2 : }
1136 2 : }
1137 : }
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